Chimney cap



y 25, 1943- G'. ROBBINS CHIMNEY CAP Filed Dec. 18, 1941 Gnovza C Ross/N5 lnvenfor attolmus Patented May 25, 1943 CHIMNEY CAP Grover 0. Robbins, Blowing Rock, N. 0.

Application December 18, 1941, Serial No. 423,423

3 Claims.

Thi invention relates to an improved chimney cap and more especially to a structure of this class having means for stimulating the draft in the chimney.

It is a well known fact that ordinary chimneys frequently have insufficient upward draft therein to overcome the down-draft produced by outside currents of air. When a gale of wind blows across the top of a chimney flue there is a tendency for the chimney walls to deflect a portion of this wind downwardly into the flue and thus retard the upward draft. Sometimes the down-draft is sufiicient to completely overcome the upward draft, resulting in the chimney draft reversing its direction of travel and filling the house with smoke.

It is an object of this invention to provide a chimney cap so constructed that the outside currents will be directed upwardly when striking the chimney wall, to thereby assume a parallel direction of travel to the up-draft currents in the chimney flue. With this type of construction, the outside air currents will assist rather than obstruct the up-draft in the chimney.

It is another object of this invention to provide a chimney cap which is formed from a pair of flush-top telescopically mounted frustro-pyramidal members, said members having the proximate faces thereof spaced apart to provide a passageway for outside air currents.

It is another object of this invention to provide a chimney cap which is formed from a hollow frustro-pyramidal member supported by the chimney and which acts as a smoke flue, a second frustro-pyramidal member telescopically mounted to form an air passageway, and flat members supported by the top of the chimney for holding the two frustro-pyramidal members in spaced relation to each other.

It is another object of this invention. to provide a chimney cap as above described in which the size of the air passageway between the frustro-pyramidal members may be changed to suit the particular chimney upon which the cap is to be placed. and at the same time maintain a flush top relation between the spacer members and the frustro-pyramidal members.

It is still another object of this invention to provide a chimney cap of the class described which can be erected piece by piece very much in the same manner as in brick laying, thereby eliminating the necessity of assembling the entire cap before mounting the same upon the chimney.

Some of the objects of the invention having been stated, other objects will appear as the description proceeds when taken in connection with the accompanying drawing, in which Figure 1 is an isometric view showing my improved chimney cap associated with the top of a chimney;

Figure 2 is a transverse vertical sectional view taken along the line 2-2 in Figure 1;

Figure 3 is an isometric view or the inner flue of my improved chimney cap;

Figure 4 is an elevation, showing certain portions thereof in section, illustrating a slightly modified form of chimney cap as it appears when associated with the top of a chimney;

Figure 5 is an isometric view of one of the spacer members associated with the form of chimney cap shown in Figure 4.

Referring more particularly to the drawing, the numeral l0 denotes the upper portion of an ordinary chimney having conventional vertical fiues I! and 52 therein. These fiues may or may not be arranged in a symmetrical relation to the chimneys; however, in case a fiue should be placed in an unsymmetrical relation to the sidewalls of the chimney the present invention is constructed to compensate for this variation.

Disposed on top of the chimney it! and surrounding the upper end of flues H and i2 is a hollow frustro-pyramidal member !4. The inner surface of this member is is bell-shaped and when installed upon the chimney it serves to conduct the smoke and gases upwardly from the flues II and E2. The outer surface of the member M has a plurality of substantially vertically disposed grooves 16 therein into which the inner edges of flat spacer members 18 are adapted to removably fit. Similar grooves I!) are provided at each corner of the frustro-pyramidal member l4. Likewise in each of these grooves IS a similar flat spacer member 29 is adapted to fit. It will be noted that the spacer members l8 and 20 project downwardly and have lateral flanges or foot portions 2! and 22, respectively, integral therewith. These flange portions rest directly on top of the chimney ill; thereby causing the spacer members to form a tie between the top of the chimney and a second frustro-pyramidal member 2G resting on the upper edges thereof. The members !8 and 20 may be secured to the top of the chimney by any suitable means such a anchor bolts Zla and 22a or if desired a suitable mortar may be em loyed with equally good results. Particular attention called to the fact that the upper outer edges of the flat spacer members l8 and 2B are curved in the proper manner to fit the interior walls of the second frustropyramidal member 23; therefore, when the member 24 is placed thereon it will be supported by the upper outer edges of all of the members 18 and 20.

Figure 2 illustrates the relative positions of the inner frustro-pyramidal member I4 and the outer frustro-pyramidal member 2d. It is here seen that the spacer members i8 and 23 form an upwardly inclined space between the frustro-pyram idal members into which horizontal currents of wind are adapted to pass. Since the outer surface of the inner member [4 is curved gradually upwardly, the currents of air which enter the space between the frustro-pyramidal members will be directed upwardly in parallel relation to the gases or products of combustion which pass upwardly from flues l l and I2.

In order to provide a suitable opening for receiving the horizontal currents of wind or air, the lower rim or the outside frustro-pyramidal member 2@ is curved to a substantially horizontal position and also to terminate the lower rim at a point above the top of the chimney. I'he top of the members i4, i8, 29 and 24 are all flush, thereby insuring the currents of air will not mix with the currents from the chimney until the upper extremity of the chimney top has been reached. In this fashion the air currents which usually blow horizontally, will enter between the lower rims of the frustro-pyramidal members [4 and 24 and then be conducted upwardly in parallel relation to the chimney currents to thereby stimulate the draft in the chimney. It is also to be noted that the space between the inner and outer frustropyramida1 members gradually converges as it progresses upwardly thereby causing the currents of air which enter below the bottom rim of the outer pyramidal member to increase in velocity while moving upwardly.

Figures 4 and 5 show a slightly modified form of the invention in which an improved means is provided whereby the space between the inner and outer pyramidal members may be varied to suit conditions. In this form of the invention, an inner frustro-pyramidal member 30 is provided, said member being adapted to rest on top of the chimney and surround the flues such as designated by reference characters II or 2. The

member 33 has grooves Si in its outer periphery into which the inner edges of flat members 32 are adapted to fit, very much in the same manner as in the preceding form of the invention. This flat member 32 likewise has lateral flanges 2| integral with the bottom portion thereof.

These flanges are used as a base which rests on top of the chimney. At the corners of the frustro-pyramidal member 30 similar spacer members 33 are provided, each of which has a flanged base 22 for supporting the same on top of the chimney.

The upper outer edges of the spacer members 32 and 33 are used for supporting the inner surface. of a second frustro-pyramidal member 38.

This member 33 has substantially the same shape :1-

as the outer member 24 previously described. In

The Width of each of the ends of the flat spacer members 32 and 33.

33 is substantially the same as the distance between the inner and outer frustro-pyramidal members. Therefore, the posts 4| and 52 serve as a support for the lower rim whereas the upper outer edges of the members 32 and 33 serve as a support for the upper rim of the member 33. Each of the members 32 and 33 has suitable break lines or grooves 35a, 35b and 350 formed therein on opposed sides of posts 4! and 62. These grooves diminish the thickness of the spacer members to make it more easily broken along desired lines. Similar equally spaced break lines 33a, 36b and 350 are formed in the upper The inner frustro-pyramidal member has suitable equally spaced break lines 30a, 39b and 300 formed in its upper portion and at the same distance from the top edge of the cap as the break lines 36a, 36b and 360. For example, when it is desired to lower the outer-frustro-pyramidal member 38 and thereby decrease the space between the inner and outer members, it is only necessary to break off the posts t! and G2 along break lines 35a and then break oil the upper extremities Of the same spacer members along break lines 36a. This will permit the upper frustro-pyramidal member 33 to be lowered a predetermined amount. Then, in order to have all of the members flush top it will be necessary to break off the upper rim of the inner pyramidal member 30 along the break line 36a. If it is desired to lower the outer member 33 still further, the posts M and 52 can be broken along break line 351) or 350 and at the same time break off the upper ends of the posts along lines 36b and 360. Then, in order to make the chimney flue top, a corresponding breaking of the inner gnember 30 will be necessary along line 331) or Particular attention is called to the shape of the outer surfaces of upper cap members 24 and. 33 in the two forms of the invention. It will be noted that these exterior surfaces are curved upwardly substantially in parallel with the inner peripheries of these caps. In other words, when the horizontal currents of wind strike these caps, the outer and upwardly disposed peripheries will direct the currents upwardly in parallel with the currents of air which pass between the cap members and thereby serve to prevent the smoke gases which flow upwardly through the inner flues l4 and 39 from being driven downwardly into the chimney.

Another outstanding advantage of my improved chimney cap is its adaptability to chimneys having a plurality of flues which are spaced unsymmetrically of the chimney. As heretofore stated, the entire assembly is adapted to rest on top of the chimney, instead of projecting downwardly on the interior of the chimney flue or on the exterior of the chimney as is the case in many conventional chimney caps. The outwardly flared bottom ends of cap members l4 and 30 permit this cap to surround the upper ends of all of the chimney flues, regardless of the unsymmetrical position. Since the inner cap members do not extend downwardly into the flue, the entire cap assembly may be positioned symmetrically of the chimney and yet serve all of the chimney flues. Of course, the chimney flues may be slightly oiT-set relative to the vertical center line of the inner cap member, but the flared bottom portion thereof will serve to collect the upwardly flue chimney gases and direct them upwardly. In other words, the exterior appearance of this chimney cap will be entirely symmetrical relative to the chimney regardless of the position of the chimney fiues.

In the drawing and specification there has been set forth a preferred embodiment of the invention and although specific terms are employed, they are used in a eneric and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims,

I claim:

1. A chimney cap comprising a hollow frustropyramidal member adapted tosurround the upper end of the chimney flue and to fit on top of the chimney closely adjacent the fiue opening, a plurality of spacer members supported by the top surface of the chimney and arranged exteriorly of said member, a second hollow frustropyramidal member resting upon said spacers and having its lower rim terminating a substantial distance above the top of the chimney, said second member having its upper rim flush-top with said first member.

2. A chimney cap comprising a hollow frustropyramidal member adapted to surround the upper end of the chimney flue and to fit on top of the chimney closely adjacent the flue opening, the outer wall of said member having a plurality of vertically disposed grooves therein, a plurality of fiat spacer members supported by the top surface of the chimney and each having one edge thereof resting in one of said grooves, a second hollow frustro-pyramidal member resting upon said spacers and having its lower rim terminating a substantial distance above the top of the chimney, said second member having its upper rim flush-top with said first member.

3. A chimney cap comprising a pair of flush-top telescopically arranged frustro-pyramidal members, the bottom edge of the outer frustro-pyramidal member being disposed above the bottom edge of the inner frustro-pyramidal member, a plurality of flat spacer members, each having opposed edges thereof abutting the proximate faces of said frustro-pyramidal members, each of said spacer members having a break line at a predetermined distance from the outer edge thereof, each of said spacer members also having a second break line at a predetermined distance from the top edge of said inner frustro-pyramidal member corresponding to the first-named break line, said inner frustro-pyramidal member having a third break line at a predetermined distance from its top rim corresponding to the first and second break lines, whereby the edges of said spacer members can be broken off to allow the outer frustro-pyramidal member to be moved closer to said inner frustro-pyramidal member and whereby the top edge of said inner frustro pyramidal member can be broken ofi along a line flush-top with said lower outer member.

GROVER C. ROBBINS. 

